The present application relates to a polymer actuator, and particularly to a polymer actuator that is bent or deformed according to an electric field applied thereto.
A polymer actuator using an ion conductive polymer (ion exchange resin) is drawing attention as a new actuator because the polymer actuator has light weight and generates great force, for example. In general, the polymer actuator has electrode layers disposed on both surfaces of an ion conductive polymer layer formed by containing an ion conductive medium such as water or the like and ions in an ion conductive polymer (ion exchange resin) film. In the polymer actuator, by applying a voltage between the pair of electrode layers, ions move within the ion conductive polymer layer, whereby the ion conductive polymer layer is bent or deformed.
However, such an existing polymer actuator has water as ion conductive medium, and thus has a problem of not being operational when the water is evaporated and dried up. Accordingly, a polymer actuator using an ionic liquid in related art has been proposed (see, for example Japanese Patent Laid-Open No. 2007-143300, hereinafter referred to as Patent Document 1, Japanese Patent Laid-Open No. 2007-329334 as Patent Document 2, Japanese Patent Laid-Open No. 2008-086185 as Patent Document 3, and Japanese Patent Laid-Open No. 2008-251697 as Patent Document 4). The ionic liquid is a salt in liquid form at normal temperature, and is nonvolatile. Thus, reliability can be improved by using this ionic liquid.
Further, polymer actuators described in Patent Documents 1 and 2 have electrode layers formed by applying a composition obtained by dispersing carbon powder into an ion conductive polymer to both surfaces of an ion conductive polymer film. Thus forming the electrode layers with the ion conductive polymer and the carbon powder can improve productivity and reduce manufacturing cost.